1. Field of the Invention
The invention relates to recovery of hydrocarbons from a subterranean formation wherein an aqueous fluid is thickened and injected into an injection well and hydrocarbons are produced from a production well.
In a more specific aspect, the invention relates to an improvement in filterability of such organic polymers by addition of a surfactant to an aqueous mixture of the organic polymer prior to filtration.
2. Brief Description of the Prior Art
Enhanced recovery of hydrocarbons from subterranean formations by injection of water into an injection well and recovery of the hydrocarbons from a production well is well known. Also well known is addition of certain organic polymers to at least a portion of the aqueous fluid which is injected to thicken the waterflood and to further enhance recovery of hydrocarbons. Such thickened aqueous floods are commonly known as polymer floods.
Also well known is combination of such polymer flooding techniques with surfactant flooding and the like to further enhance recovery of hydrocarbons.
One problem with injection of such aqueous floods containing organic polymers is plugging of the formation injected into. This problem can be particularly troublesome with biopolymers of which the Xanthan gums or heteropolysaccharides produced by fermentation with Xanthomonas campestris are a very commercially important example.
To mitigate the problem of plugging of the formation injected into, aqueous solutions of such organic polymers are commonly filtered prior to injection.
However, the filters employed to remove the plugging components also rapidly lose capacity and often become plugged.
The improvement of the instant invention results in considerable enhancement of such filtration.